1. Field of the invention
The present invention relates to a test system and a test method using a virtual review, and more specifically, to a test system and a test method using a virtual review for testing whether there is a defect on a thin film transistor substrate or a color filter substrate.
2. Related Art
With the recent increase of interest in information display devices, flat panel displays (FPDs) have been studied and commercialized as a means to replace existing display devices such as CRTs. Among these flat panel displays, a liquid crystal display (LCD), which requires optical anisotropy of the liquid crystal to display an image, has been widely used as a monitor for laptop computers, desktop computers, etc. because of its good resolution, capability of displaying an image, and image quality.
A liquid crystal display typically comprises an array substrate, a color filter substrate, and a liquid crystal layer between the array substrate and the color filter substrate.
The array substrate comprises: gate lines and data lines, both arranged on the array substrate in horizontal and vertical directions to define pixel regions; switching elements such as thin film transistors arranged on the intersection regions of the gate lines and data lines; and pixel electrodes formed on the pixel regions.
The color filter substrate comprises: a color filter comprising sub-filters R, G, B to implement colors; and a black matrix to separate between the sub-filters to thereby define pixel regions and to block light transmitting the liquid crystal layer. The color filter substrate can further comprise transparent common electrodes, which are arranged on the array substrate, to apply voltages to the liquid crystal layer.
The array substrate and color filter substrate configured as above are attached to each other by a sealant to thereby complete a liquid crystal panel.
The liquid crystal display can generally be manufactured through an array process, a color filter process, a cell process, and a module process.
The array process is a process that forms arrays of thin film transistors on a first substrate, which is a transparent insulating substrate, by repeating deposition, photolithography, and etching. The color filter process is a process that forms a black matrix to block light from passing through regions other than pixel regions and to make red, green, and blue color filters (R, G, B) using dyes or pigments.
Before the cell process, an additional process is required to evaluate the state of the manufactured array substrate and color filter substrate. The array and the color filter are tested to determine whether there is a defect on the array substrate and color filter substrate, to eliminate substrates having defects from the cell process.
The cell process is a process used to form liquid crystal panel cells. In this process the first substrate, which has been completed through the thin film transistor process, is attached to the second substrate, which has been completed through the color filter substrate. The substrates are attached such that they have a constant gap therebetween and then liquid crystal is injected or dropped therebetween. The module process is a process used to form modules by providing a circuit unit for signal processing, connecting the liquid crystal panel and circuit unit through a well-known mounting scheme, and then attaching them to a feature.
The above cell process will be described below in more detail.
First, alignment films are disposed on each of the array substrate, formed through the array process, and the color filter substrate, formed through the color filter process. Then a rubbing process is used to provide an anchoring force or surface adhesive force to liquid crystal molecules of the liquid crystal layer, which is provided between the array substrate and color filter substrate. At this time, the alignment films can undergo washing before applying, alignment film printing, and alignment film testing, and rubbing in the above-stated order.
Subsequently, the array substrate and color filter substrate each are washed out, a spacer is provided to keep cell gaps constantly on the array substrate, and a sealing material is applied to the circumference of the color filter. Then, the array substrate and color filter substrate are pressured to be attached to each other.
Finally, liquid crystal is injected into each liquid crystal panel through liquid crystal inlets and the inlets are sealed to form a liquid crystal layer.
Before the cell process is performed, the array substrate and color filter substrate are tested to determine whether there are any defects. More specifically, the array substrate and color filter are examined to determine whether there is any fault on their appearances and electrical wirings. For example, the process is performed to determine the appearance of color filter protrusions, oblique line stains, rubbing strips, pin holes, short circuits or disconnections in the gate lines and data lines and the like.
A test system for performing the testing process comprises a group of test devices for testing whether there is a defect on the array substrate and color filter substrate and a repair system for repairing the substrates if a fault occurs on the substrates.
The group of test devices comprises a test device for testing whether the array substrate and color filter substrate have any defect or not, a system computer for driving the test device, and a monitor connected to the system computer. Here, a keyboard and a mouse are added to the system computer to operate the system computer. In addition, a review monitor is added to the group of test devices, through which an operator can see whether there is a defect on the substrates.
In a prior art test system, one review monitor was connected to only one computer for repair in a one-to-one manner, so that one inspector could control only one test device. Therefore, there existed a problem in that work efficiency was decreased due to time loss, for example, because the test device doesn't operate during the inspector's meal times or break times. Furthermore, the prior test system had a problem in that it required inspectors as many as the number of test devices.